Methods for repairing water-cooled generator stator bar clips

ABSTRACT

An apparatus for repairing a liquid cooled compressor stator bar bottle clip having a groove extending around an outer surface of the bottle clip is provided. In an exemplary embodiment, the repair apparatus includes a first body portion that includes a plurality of threaded fastener openings in a first end section and a second end section of the first body portion, a second body portion that includes a plurality of threaded fastener openings in a first end section and a second end section of the second body portion, and a plurality of threaded fasteners extending through corresponding fastener openings in the first and second body portions. The fasteners connect the first and second body portions such that an elliptical opening is defined between the first and second body portions. The elliptical opening extends through the repair apparatus.

BACKGROUND OF THE INVENTION

This invention relates generally to apparatus and methods of repairing astator bar of a generator, and particularly to apparatus and methods forrepairing the stator bar clips.

Water-cooled stator bars for electrical generators include a pluralityof small rectangular solid and hollow copper strands which are brazed toone another within the stator bar and brazed to the interior walls of anend fitting. The brazing material typically used is a copper phosphorousalloy. The end fitting serves as both an electrical and a hydraulicconnection for the stator bar. The end fitting typically includes anenclosed chamber for ingress or egress of stator bar cooling liquid,typically deionized water. Thus, the end fitting provides a hollowchamber which serves to manifold the water passages of the strands. Anopening of the end fitting receives the ends of the strands of thestator bar, the fitting and peripherally outermost copper strands of thestator bar being brazed to one another. A second opening includes a clipfor connecting the bar to series loops/phase connections and a coolingwater supply. This clip is often referred to as the stator bar bottleclip. Over time, leaks have variously developed about the connectionbetween the stator bar ends and the stator bar end fitting as well asbetween adjacent strands. The end fitting-to-strand and strand-to-strandjoints have the highest potential for causing damage should a leak occurbecause a leak at this location will flow directly into the ground wallinsulation of the winding. The result is the degradation of thedielectric strength of the insulation which will eventually lead tofailure. Also, the braised connections between the bar bottle clip toseries loops/phase connections and cooling water supply piping can beweakened by excessive tolerances between the fixtures which requires theuse of excessive braise alloy thereby causing a weak joint. Further,oversized and elliptical shaped bar clips can cause fitup problems andweak braised joints.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, an apparatus for repairing a liquid cooled compressorstator bar bottle clip having a groove extending around an outer surfaceof the bottle clip is provided. The repair apparatus includes a firstbody portion that includes a plurality of threaded fastener openings ina first end section and a second end section of the first body portion,a second body portion that includes a plurality of threaded fasteneropenings in a first end section and a second end section of the secondbody portion, and a plurality of threaded fasteners extending throughcorresponding fastener openings in the first and second body portions.The fasteners connect the first and second body portions such that anelliptical opening is defined between the first and second bodyportions. The elliptical opening extends through the repair apparatus.

In another aspect a method of repairing a liquid cooled compressorstator bar bottle clip having a groove extending around an outer surfaceof the stator bar bottle clip is provided. The method includespositioning a repair apparatus around the stator bar bottle clip,tightening the repair apparatus so that at least a portion of the repairapparatus contacts the outer surface of the stator bar bottle clip, androtating the repair apparatus around the outer surface of the stator barbottle clip. The repair apparatus includes a first body portion thatincludes a plurality of threaded fastener openings in a first endsection and a second end section of the first body portion, a secondbody portion that includes a plurality of threaded fastener openings ina first end section and a second end section of the second body portion,and a plurality of threaded fasteners extending through correspondingfastener openings in the first and second body portions. The fastenersconnect the first and second body portions such that an ellipticalopening is defined between the first and second body portions. Theelliptical opening extends through the repair apparatus.

In another aspect, an apparatus for repairing a liquid cooled compressorstator bar bottle clip having a groove extending around an outer surfaceof the bottle clip is provided. The repair apparatus includes a firstbody portion that includes a plurality of threaded fastener openings ina first end section and a second end section of the first body portion,a second body portion that includes a plurality of threaded fasteneropenings in a first end section and a second end section of the secondbody portion, and a plurality of threaded fasteners extending throughcorresponding fastener openings in the first and second body portions.The fasteners connect the first and second body portions such that anelliptical opening is defined between the first and second bodyportions. The elliptical opening extends through the repair apparatus.The repair apparatus also includes at least one guide pin extending froman inner surface of the elliptical opening. The at least one guide pinis sized and positioned to be received in the groove in the stator barbottle clip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a liquid-cooled generator with parts cutaway

FIG. 2 is a sectional schematic view of the liquid cooled stator bar endfitting shown in FIG. 1.

FIG. 3 is a top view of a bar clip repair tool in accordance with anembodiment of the present invention.

FIG. 4 is a perspective view of the repair tool shown in FIG. 4 in adisassembled state.

FIG. 5 is a view of the repair tool shown in FIG. 4 attached to theliquid cooled stator end fitting shown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

A repair apparatus and method of repairing a liquid cooled compressorstator bar bottle clip is described in detail below. The repairapparatus includes two body portions that are connected together by aplurality of fasteners. An elliptical opening is formed by the two bodyportions and is sized for the predetermined outer diameter of a bottleclip. The two body portions are positioned around the bottle clip andtightened. The apparatus is then rotated around the bottle clip toresize and reshape the bottle clip. After several rotations of therepair apparatus have been completed, the apparatus is retightened andthe apparatus is again rotated around the bottle clip. The repairapparatus corrects oversized and elliptically shaped stator bar bottleclips on site which increases productivity and reduces the cost ofcorrecting the problem of oversized and incorrectly shaped bottle clips.

Referring now to the drawings, FIG. 1 is a schematic view of aliquid-cooled generator 10 with parts cut away. In an exemplaryembodiment, generator 10 includes a liquid cooled stator windingarrangement 12 that includes a stator core 14 having stator core flanges16 and stator core ribs 18. Stator bars 20 pass through radiallyextending slots 22 in stator core 14. Inlet and outlet fittings 24 and26, also referred to as bottle fittings 24 and 26, are connected tostator bars 20 by stator bar end fittings 28. Inlet hoses 30 connectinlet fitting 24 to an inlet coolant header 32, and outlet hoses 34connect outlet end fitting 26 to an outlet coolant header 36. Stator barend fittings 28 are formed of a electrically conductive material suchas, for example, copper or brass.

Referring to FIG. 2, stator bar end fittings 28 includes a body 38having a first end portion 40 and a second end portion 42. First endportion 40 includes a rectilinear opening 44 sized to receive a statorbar 20. Second end portion 42 includes an inlet/outlet port 46. Port 46is also referred to as bottle clip 46 and is sized to connect to bottlefittings 24 and 26. Bottle clip 46 serves as both an electricalconnection and a hydraulic conduit for flowing liquid coolant, forexample, deionized water, into or from a chamber 48 defined by walls 50of fitting 28 and stator bar 20. Liquid either flows into fitting 28through chamber 48 and into stator bar 20 for cooling purposes whenfitting 28 is an inlet fitting, or flows from stator bar 20 throughchamber 48 and out bottle clip 46 when fitting 28 is employed as anoutlet fitting. Bottle fittings 24 and 26 (shown in FIG. 1) are sized toengage an outer surface 52 of bottle clip 46. Typically, the jointbetween bottle fittings 24 and 26 with bottle clips 46 are sealed bybraising. A groove 54 extends around outer surface 52 of bottle clip 46.

FIG. 3 is a top view of a bottle clip repair apparatus 60 in accordancewith an embodiment of the present invention, and FIG. 4 is a perspectiveview of repair apparatus 60 shown in a disassembled state. Referring toFIGS. 3 and 4, repair apparatus 60 includes a first body portion 62 anda second body portion 64 coupled together by a plurality of fasteners66. First body portion 62 includes a first end section 68, a second endsection 70 and a center section 72. A plurality of threaded fasteneropenings 74 are located in first and second end sections 68 and 70.Fastener openings 74 are sized to threadedly receive fasteners 66.Center section 72 includes an arcuate inner surface 76 with a guide pin78 extending from inner surface 76.

Second body portion 64, similar to first body portion 62, includes afirst end section 80, a second end section 82 and a center section 84. Aplurality of threaded fastener openings 86 are located in first andsecond end sections 80 and 82. Fastener openings 86 are sized tothreadedly receive fasteners 66. Center section 84 includes an arcuateinner surface 88 with a guide pin 90 extending from inner surface 88. Inthe exemplary embodiment, each threaded fastener opening 74 in firstbody portion 62 is aligned with a corresponding treaded fastener opening86 in second body portion 64. Repair apparatus 60 is assembled byextending fasteners 76 through aligned fastener openings 74 and 86 infirst and second body portions 62 and 64 respectively. An ellipticalcenter opening 92 is defined between first and second body portions 62and 64. Repair apparatus 60 can be fabricated from any suitable materialthat is harder than bottle clip 46, for example, steel, stainless steel,and the like.

To repair bottle clip 46, repair apparatus 60 is positioned aroundbottle clip 46 with inner surfaces 76 and 88 of first and second bodyportions 62 and 64 contacting an outer surface 62 of bottle clip 46 andwith guide pins 78 and 90 positioned in groove 54. Fasteners 66 aretightened causing first and second body portions 62 and 64 to exert aforce on bottle clip 46. Repair apparatus 60 is then rotated aroundbottle clip 46 to resize and reshape bottle clip 46. Guide pins 78 and90 ensure proper placement and alignment as apparatus 60 is rotated.After several rotations, fasteners are retightened and apparatus 60 isagain rotated around bottle clip 46. The tightening and rotating ofapparatus 60 is repeated until the predetermined size and/or shape ofbottle clip has been achieved. The elliptical shape of center opening 92provides the force to reshape bottle clip 46 while permitting enoughclearance at the matting joint to allow bottle clip 46 to flex duringthe reshaping process. In the exemplary embodiment, the major axis ofelliptical opening 92 extends between first and second end sections offirst and second body portions 62 and 64 when fasteners 66 arecompletely tightened with first end sections 68 and 80 and second endsections 70 and 82 adjacent each other. FIG. 5 shows repair apparatus 60in a completely tightened state on bottle clip 46.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1-7. (canceled)
 8. A method of repairing a liquid cooled compressorstator bar bottle clip, the stator bar bottle clip comprising a grooveextending around an outer surface of the stator bar bottle clip, saidmethod comprising: positioning a repair apparatus around a stator barbottle clip; tightening the repair apparatus so that at least a portionof the repair apparatus contacts the outer surface of the stator barbottle clip; and rotating the repair apparatus around the outer surfaceof the stator bar bottle clip, the repair apparatus comprising: a firstbody portion comprising a plurality of threaded fastener openings in afirst end section and a second end section of the first body portion; asecond body portion comprising a plurality of threaded fastener openingsin a first end section and a second end section of the second bodyportion; and a plurality of threaded fasteners extending throughcorresponding fastener openings in the first body portion and the secondbody portion, the fasteners for connecting the first and second bodyportions such that an elliptical opening is defined between the firstand the second body portions, the elliptical opening extending throughthe repair apparatus.
 9. A method in accordance with claim 8 furthercomprising: retightening the repair apparatus; and rotating theretightened repair apparatus around the outer surface of the stator barbottle clip.
 10. A method in accordance with claim 9 further comprising:(a) retightening the repair apparatus; (b) rotating the retightenedrepair apparatus around the outer surface of the stator bar bottle clip;and (c) repeating (a) and (b) until a predetermined diameter of thebottle clip is achieved.
 11. A method in accordance with claim 8 whereinthe repair apparatus further comprises at least one guide pin extendingfrom an inner surface of the center opening, the at least one guide pinsized and positioned to be received in the groove in the stator barbottle clip, and positioning a repair apparatus around a stator barbottle clip further comprises positioning the repair apparatus around astator bar bottle clip so that the at least one guide pin is positionedin the groove in the outer surface of the stator bar bottle clip.
 12. Amethod in accordance with claim 11 wherein the repair apparatus furthercomprises a first guide pin located in said first body portion and asecond guide pin located in said second body portion, and positioning arepair apparatus around a stator bar bottle clip further comprisespositioning the repair apparatus around a stator bar bottle clip so thatthe first and second guide pins are positioned in the groove in theouter surface of the stator bar bottle clip.
 13. A method in accordancewith claim 8 wherein tightening the repair apparatus comprisestightening the plurality of threaded fasteners in the plurality ofthreaded fastener openings to move first body portion and second bodyportion closer together so as to exert a force on the outer surface ofthe bottle clip.
 14. A method in accordance with claim 13 wherein eachsaid threaded fastener opening of said first body portion is alignedwith a corresponding threaded fastener opening of said second bodyportion.
 15. A method in accordance with claim 8 wherein the ellipticalopening comprises a major axis and a minor axis, the major axisextending between the first and second end section of the first andsecond body portions when the first end section of the first bodyportion is adjacent the first end section of the second body portion andthe second end section of the first body portion is adjacent the secondend section of the second body portion. 16-21. (canceled)